The present invention relates to the monitoring of claimed passenger occupancy of motor vehicles that are traversing a section of highway that has been designated as one that is advantageous for high occupancy vehicles. An entity (such as a municipality, or state or federal transportation board) may wish to encourage ridesharing by providing incentives to individuals who participate in ridesharing. Some entities currently provide incentives in the form of specially designated lanes where travel may be restricted to high occupancy vehicles, or reduced tolls on toll roads. But in non toll-road environments and on highways without the capacity for designation of high occupancy lanes, other incentives such as reimbursements, tax credits, or special parking privileges could be awarded as incentives for ridesharing if there was a means for reliably identifying ridesharing events that were deemed qualified to receive an incentive.